1. Field of the Invention
The invention relates to a thermally-assisted magnetic recording head in use for the thermally-assisted magnetic recording that reduces a coercive force of a magnetic write medium by irradiating near-field light to perform information writing, and a head gimbals assembly, a head arm assembly, and a magnetic disk device that are provided with the thermally-assisted magnetic recording head, as well as a method of manufacturing the thermally-assisted magnetic recording head.
2. Description of the Related Art
In the past, a magnetic disk device has been used as a means for writing and reading magnetic information (hereinafter referred to as “information” simply). The magnetic disk device is provided, within a housing for example, with a magnetic disk to store the information thereon, and a magnetic reading/recording head to write the information on the magnetic disk and to read the information written on the magnetic disk. The magnetic disk, which is supported on a rotary shaft of a spindle motor fixed within the housing, is intended to rotate on the rotary shaft. On the other hand, the magnetic reading/recording head, which is formed on one side surface of a magnetic head slider provided at one end of a suspension, is configured including a magnetic write element and a magnetic read element each having an air bearing surface (ABS: Air Bearing Surface) in opposition to the magnetic disk. In particular, as the magnetic read element, an MR element exhibiting a magnetoresistive (MR: Magnetoresistive) effect is generally used. The other end of the suspension is attached to the front end of an arm supported to be rotatable on a fixed shaft that is provided in a standing state within the housing.
When the magnetic disk device is placed in a stationary state, i.e., when the magnetic disk does not rotate, but stands still, the magnetic reading/recording head is not present on the magnetic disk, but is placed in an external refuge state (unload state). Then, if the magnetic disk device is placed in a driven state, and the magnetic disk starts its rotation, the magnetic reading/recording head is placed in a state of movement to a given position on the magnetic disk along with the suspension (load state). On reaching the predetermined rotating speed of the magnetic disk, the magnetic head slider is stabilized in a state of being lifted slightly from the top surface of the magnetic disk by virtue of the balance between positive pressure and negative pressure, thereby assuring to accurately perform write and read operation of the information.
With the increasing write density (increasing capacity) of the magnetic disk in recent years, improved performance of the magnetic reading/recording head and the magnetic disk has been demanded. The magnetic disk is a discrete medium with a collection of magnetic particulates, each of which is of a single magnetic domain structure. In this magnetic disk, a single write bit is configured by a plurality of magnetic particulates. To increase the write density, the irregularity on a boundary of the adjacent write bits has to be reduced, and thus the magnetic particulates have to be reduced in size. However, reduction in size of the magnetic particulates leads to decrease in volume of the magnetic particulates, causing the thermal stability of magnetization for the magnetic particulates to deteriorate as an issue, accordingly. In solving such an issue, it is useful to increase the anisotropic energy of the magnetic particulates. However, increased anisotropic energy of the magnetic particulates results in increased coercive force of the magnetic disk, causing an issue that information write operation becomes difficult in the existing magnetic heads.
As a method for solving the issue as mentioned above, a method of what is called the thermally-assisted magnetic recording is proposed. Such a method uses a magnetic write medium with a large coercive force, and applies the magnetic field and heat simultaneously to a portion on which the information is written on the magnetic write medium at the time of information write operation to write the information with temperature at that portion increased and a coercive force decreased. The magnetic head in use for the thermally-assisted magnetic recording is hereinafter referred to as the thermally-assisted magnetic recording head.
In performing the thermally-assisted magnetic recording, a method using the near-field light is commonly used as a method for applying heat to the magnetic write medium. As a method for generating the near-field light, a method using a near-field light probe that is a piece of metal, what is called a plasmon generator, is generally known. The plasmon generator generates the plasmon through excitation by means of external incident light, resulting in generation of the near-field light. A light source for supplying the external incident light is necessary, and various embodiments in regard to mounting of the light source have been proposed to date. Until now, the applicant has proposed, for example, a thermally-assisted magnetic recording head having a “composite slider structure” to bond a light source unit with a laser oscillator with the surface on the side opposite to the ABS of the slider on which the magnetic write element is formed. The “composite slider structure” has been disclosed, for example, in US Patent Application Publication No. 2008/043360 specification and in US Patent Application Publication No. 2009/052078 specification.
In a method for performing the thermally-assisted magnetic recording using the plasmon generator, it is important to stably supply the light with sufficient intensity to a desired position on the magnetic write medium. For this purpose, high alignment accuracy has to be assured in fixing the light source unit to the slider. One reason comes from the fact that deterioration in the alignment accuracy may lead to degradation in heating efficiency for the magnetic write medium, causing a major issue in performing the thermally-assisted magnetic recording. For such a reason, the thermally-assisted magnetic recording head has been desired that is excellent in the write efficiency in spite of a compact configuration as well as being simply manufacturable. In addition, a simple method of manufacturing such a thermally-assisted magnetic recording head has been also desired.